1. Field of the Invention
The present invention relates to a lighting fixture for vehicles for signaling purposes, such as vehicle-mounted tail lamp, brake lamp, turn signal and high-mount stop lamp, used to signal other vehicles and pedestrians of one's intended action, or to a lighting fixture for use as a variety of illumination lamps.
2. Description of the Relates Arts
Conventionally, when a vertical or horizontal lighting fixture for vehicles is configured using light-emitting components such as LEDs, a number of LEDs are arranged in the direction of the length, and light emitted sideward by the LEDs is reflected by a reflecting material such that it is radiated forward. Such a configuration, when LEDs emit light, allows part of light from the LEDs to be directly reflected and some other part of light to be reflected by a reflecting material such that light is radiated forward, as a result of which the entire, vertical or horizontal light-emitting surface can appear illuminated.
An example of such a configuration is shown in FIG. 19 and represented here by a lighting fixture for vehicles 100 which uses an incandescent lamp as light source 91 and is provided with a parabolic reflecting surface 92 such as paraboloid of revolution, whose focus is the light source 91, to generate parallel light headed in the direction of illumination of this lighting fixture for vehicles 100.
Moreover, an outer lens 93 is provided to cover the front of the reflecting surface 92 so that light is diffused properly by lens cuts 93a, provided in the outer lens 93, for example, in the form of a fisheye lens, thus offering light distribution characteristic of the lighting fixture for vehicles 100.
Note that there are some lighting fixtures in which projections and depressions comparable to the lens cuts 93a are provided on the reflecting surface 92 while no lens cuts are provided on the outer lens 93a, so that light passes with no diffusion.
The lighting fixtures are disclosed in Japan Publication of Patent Applications' 1998-255512, and 1999-96808 and 2000-123610 of the same Publication and in U.S. Pat. No. 6280480.
With lighting fixtures of such a configuration, however, the intensity of light emitted forward directly by LEDs is high, and the directivity of light reflected by a reflecting material is low.
This leads to decreased utilization efficiency of light emitted by the LEDs, and consequently more LEDs are needed to secure an acceptable amount of light, thus resulting in high cost, causing more heat to be produced by LEDs and rendering the light intensity maintenance rate vulnerable to a decline.
Moreover, it looks as through LEDs shone in a dotted manner when they are viewed from the front, and since light reflected by a reflecting material is diffused, light from the reflecting surface of the reflecting material looks dark. As a result, LEDs present an obvious unevenness of light when viewed from the front.
Therefore, since LEDs look highly bright and dotted, they give an impression of being spotty, and since the reflecting surface of the reflecting material does not shine beautifully, the lighting fixture is not highly aesthetically pleasant as a whole.
To render light from LEDs uniform, it is possible, for example, to provide a lens having cuts such as fisheye Fresnel cuts forwardly of the LEDs, however, such a cuts-equipped lens can reduce design freedom of the lighting fixture as a whole.
Moreover, with the lighting fixture for vehicles 100, firstly since the parabolic reflecting surface 92 requiring an appropriate depth is employed to radiate parallel light over a wide area, the lighting fixture for vehicles 100 becomes very deep as a whole, for example, causing the fixture to protrude into the trunk room and reducing the vehicle's carrying capacity.
Secondly, when the outer lens is viewed with the fixture lit, the intensity of portions such as the incandescent lamp's filament is high, as a result of which direct light D from the light source 91 looks exceptionally bright, causing such portions to be out of proportion to other portions whose brightness is determined by reflected light R from the reflecting surface 92 and thus uglifying the fixture during illumination.